Master Cell Group Failure Recovery for Dual Connectivity Wireless Devices

ABSTRACT

Apparatuses, systems, and methods for a wireless device to perform master cell group failure recovery in a dual connectivity cellular communication system. The wireless device may establish a first wireless link to a cellular network via a first cell group. The first cell group may be configured as a master cell group for the wireless device. The wireless device may establish a second wireless link to the cellular network via a second cell group. The second cell group may be configured as a secondary cell group for the wireless device. The wireless device may determine that link failure for the first wireless link has occurred. The wireless device may perform master cell group link failure recovery using the second wireless link based at least in part on the link failure for the first wireless link.

PRIORITY DATA

This application is a continuation of U.S. patent application Ser. No.16/782,309, entitled “Master Cell Group Failure Recovery for DualConnectivity Wireless Devices,” filed Feb. 5, 2020, which claims thebenefit of priority to Chinese Application No. 201910111959.5, titled“Master Cell Group Failure Recovery for Dual Connectivity WirelessDevices”, filed Feb. 13, 2019, which is hereby incorporated by referencein its entirety as though fully and completely set forth herein. Theclaims in the instant application are different than those of the parentapplication or other related applications. The Applicant thereforerescinds any disclaimer of claim scope made in the parent application orany predecessor application in relation to the instant application. TheExaminer is therefore advised that any such previous disclaimer and thecited references that it was made to avoid, may need to be revisited.Further, any disclaimer made in the instant application should not beread into or against the parent application or other relatedapplications.

FIELD

The present application relates to wireless devices, and including toapparatuses, systems, and methods for a wireless device to performmaster cell group failure recovery in a dual connectivity cellularcommunication system.

DESCRIPTION OF THE RELATED ART

Wireless communication systems are rapidly growing in usage. Further,wireless communication technology has evolved from voice-onlycommunications to also include the transmission of data, such asInternet and multimedia content. Additionally, there exist numerousdifferent wireless communication technologies and standards. Someexamples of wireless communication standards include GSM, UMTS(associated with, for example, WCDMA or TD-SCDMA air interfaces), LTE,LTE Advanced (LTE-A), NR, HSPA, 3GPP2 CDMA2000 (e.g., 1×RTT, 1×EV-DO,HRPD, eHRPD), IEEE 802.11 (WLAN or Wi-Fi), BLUETOOTH™, etc.

In many instances, a wireless device may be able to communicate usingmultiple such technologies. However, determining how best to utilizemultiple wireless communication technologies together in a wirelessdevice in a complementary manner may be a complex task. Thus,improvements in the field are desired.

SUMMARY

Embodiments relate to apparatuses, systems, and methods for a wirelessdevice to perform master cell group failure recovery in a dualconnectivity cellular communication system.

The dual connectivity cellular communication system may supportconcurrent (or substantially concurrent) connections with multiple nodesof the same generation (e.g., fifth generation new radio (5G NR) networknodes) of cellular communication technology, or of different generations(e.g., 5G NR and LTE) of cellular communication technology, amongvarious possibilities.

When a wireless device has dual connectivity, one cell group may beconfigured as a master cell group and another cell group may beconfigured as a secondary cell group, at least in some instances. Insuch a scenario, it may be possible for radio link failure to occur witheither or both cell groups.

According to the techniques described herein, it may be possible tocontinue to use a link with one cell group while link failure isoccurring with the other cell group, including potentially if linkfailure with the master cell group occurs. This may, for example, allowthe wireless device to continue data communication and to recover themaster cell group link using the secondary cell group link, thuspotentially avoiding data interruptions and the need for a full radioresource control connection re-establishment procedure, in at least someinstances.

The techniques described herein may be implemented in and/or used with anumber of different types of devices, including but not limited tocellular phones, tablet computers, wearable computing devices, portablemedia players, and any of various other computing devices.

This Summary is intended to provide a brief overview of some of thesubject matter described in this document. Accordingly, it will beappreciated that the above-described features are merely examples andshould not be construed to narrow the scope or spirit of the subjectmatter described herein in any way. Other features, aspects, andadvantages of the subject matter described herein will become apparentfrom the following Detailed Description, Figures, and Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present subject matter can be obtainedwhen the following detailed description of various embodiments isconsidered in conjunction with the following drawings, in which:

FIG. 1 illustrates an example wireless communication system, accordingto some embodiments;

FIG. 2 illustrates a base station (BS) in communication with a userequipment (UE) device, according to some embodiments;

FIG. 3 illustrates an example block diagram of a UE, according to someembodiments;

FIG. 4 illustrates an example block diagram of a BS, according to someembodiments;

FIG. 5 illustrates an example block diagram of cellular communicationcircuitry, according to some embodiments;

FIG. 6A illustrates an example of connections between an EPC network, anLTE base station (eNB), and a 5G NR base station (gNB), according tosome embodiments;

FIG. 6B illustrates an example of a protocol stack for an eNB and a gNB,according to some embodiments;

FIG. 7 is a flowchart diagram illustrating an example method for awireless device to perform master cell group failure recovery in a dualconnectivity cellular communication system, according to someembodiments;

FIG. 8 illustrates exemplary aspects of a dual connectivity cellularcommunication system, according to some embodiments;

FIGS. 9-10 illustrate exemplary aspects of possible signaling radiobearer configurations for a dual connectivity cellular communicationsystem, according to some embodiments; and

FIGS. 11-19 are signal flow diagrams illustrating exemplary aspects of avariety of possible master cell group link recovery scenarios, accordingto some embodiments.

While the features described herein may be susceptible to variousmodifications and alternative forms, specific embodiments thereof areshown by way of example in the drawings and are herein described indetail. It should be understood, however, that the drawings and detaileddescription thereto are not intended to be limiting to the particularform disclosed, but on the contrary, the intention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the subject matter as defined by the appended claims.

DETAILED DESCRIPTION Terms

The following is a glossary of terms used in this disclosure:

Memory Medium—Any of various types of non-transitory memory devices orstorage devices. The term “memory medium” is intended to include aninstallation medium, e.g., a CD-ROM, floppy disks, or tape device; acomputer system memory or random access memory such as DRAM, DDR RAM,SRAM, EDO RAM, Rambus RAM, etc.; a non-volatile memory such as a Flash,magnetic media, e.g., a hard drive, or optical storage; registers, orother similar types of memory elements, etc. The memory medium mayinclude other types of non-transitory memory as well or combinationsthereof. In addition, the memory medium may be located in a firstcomputer system in which the programs are executed, or may be located ina second different computer system which connects to the first computersystem over a network, such as the Internet. In the latter instance, thesecond computer system may provide program instructions to the firstcomputer for execution. The term “memory medium” may include two or morememory mediums which may reside in different locations, e.g., indifferent computer systems that are connected over a network. The memorymedium may store program instructions (e.g., embodied as computerprograms) that may be executed by one or more processors.

Carrier Medium—a memory medium as described above, as well as a physicaltransmission medium, such as a bus, network, and/or other physicaltransmission medium that conveys signals such as electrical,electromagnetic, or digital signals.

Programmable Hardware Element—includes various hardware devicescomprising multiple programmable function blocks connected via aprogrammable interconnect. Examples include FPGAs (Field ProgrammableGate Arrays), PLDs (Programmable Logic Devices), FPOAs (FieldProgrammable Object Arrays), and CPLDs (Complex PLDs). The programmablefunction blocks may range from fine grained (combinatorial logic or lookup tables) to coarse grained (arithmetic logic units or processorcores). A programmable hardware element may also be referred to as“reconfigurable logic”.

Computer System—any of various types of computing or processing systems,including a personal computer system (PC), mainframe computer system,workstation, network appliance, Internet appliance, personal digitalassistant (PDA), television system, grid computing system, or otherdevice or combinations of devices. In general, the term “computersystem” can be broadly defined to encompass any device (or combinationof devices) having at least one processor that executes instructionsfrom a memory medium.

User Equipment (UE) (or “UE Device”)—any of various types of computersystems or devices that are mobile or portable and that perform wirelesscommunications. Examples of UE devices include mobile telephones orsmart phones (e.g., iPhone™, Android™-based phones), portable gamingdevices (e.g., Nintendo DS™ PlayStation Portable™, Gameboy Advance™,iPhone™), laptops, wearable devices (e.g. smart watch, smart glasses),PDAs, portable Internet devices, music players, data storage devices, orother handheld devices, etc. In general, the term “UE” or “UE device”can be broadly defined to encompass any electronic, computing, and/ortelecommunications device (or combination of devices) which is easilytransported by a user and capable of wireless communication.

Wireless Device—any of various types of computer systems or devices thatperform wireless communications. A wireless device can be portable (ormobile) or may be stationary or fixed at a certain location. A UE is anexample of a wireless device.

Communication Device—any of various types of computer systems or devicesthat perform communications, where the communications can be wired orwireless. A communication device can be portable (or mobile) or may bestationary or fixed at a certain location. A wireless device is anexample of a communication device. A UE is another example of acommunication device.

Base Station—The term “Base Station” has the full breadth of itsordinary meaning, and at least includes a wireless communication stationinstalled at a fixed location and used to communicate as part of awireless telephone system or radio system.

Processing Element (or Processor)—refers to various elements orcombinations of elements that are capable of performing a function in adevice, such as a user equipment or a cellular network device.Processing elements may include, for example: processors and associatedmemory, portions or circuits of individual processor cores, entireprocessor cores, processor arrays, circuits such as an ASIC (ApplicationSpecific Integrated Circuit), programmable hardware elements such as afield programmable gate array (FPGA), as well any of variouscombinations of the above.

Channel—a medium used to convey information from a sender (transmitter)to a receiver. It should be noted that since characteristics of the term“channel” may differ according to different wireless protocols, the term“channel” as used herein may be considered as being used in a mannerthat is consistent with the standard of the type of device withreference to which the term is used. In some standards, channel widthsmay be variable (e.g., depending on device capability, band conditions,etc.). For example, LTE may support scalable channel bandwidths from 1.4MHz to 20 MHz. In contrast, WLAN channels may be 22 MHz wide whileBluetooth channels may be 1 Mhz wide. Other protocols and standards mayinclude different definitions of channels. Furthermore, some standardsmay define and use multiple types of channels, e.g., different channelsfor uplink or downlink and/or different channels for different uses suchas data, control information, etc.

Band—The term “band” has the full breadth of its ordinary meaning, andat least includes a section of spectrum (e.g., radio frequency spectrum)in which channels are used or set aside for the same purpose.

Automatically—refers to an action or operation performed by a computersystem (e.g., software executed by the computer system) or device (e.g.,circuitry, programmable hardware elements, ASICs, etc.), without userinput directly specifying or performing the action or operation. Thusthe term “automatically” is in contrast to an operation being manuallyperformed or specified by the user, where the user provides input todirectly perform the operation. An automatic procedure may be initiatedby input provided by the user, but the subsequent actions that areperformed “automatically” are not specified by the user, i.e., are notperformed “manually”, where the user specifies each action to perform.For example, a user filling out an electronic form by selecting eachfield and providing input specifying information (e.g., by typinginformation, selecting check boxes, radio selections, etc.) is fillingout the form manually, even though the computer system must update theform in response to the user actions. The form may be automaticallyfilled out by the computer system where the computer system (e.g.,software executing on the computer system) analyzes the fields of theform and fills in the form without any user input specifying the answersto the fields. As indicated above, the user may invoke the automaticfilling of the form, but is not involved in the actual filling of theform (e.g., the user is not manually specifying answers to fields butrather they are being automatically completed). The presentspecification provides various examples of operations beingautomatically performed in response to actions the user has taken.

Approximately—refers to a value that is almost correct or exact. Forexample, approximately may refer to a value that is within 1 to 10percent of the exact (or desired) value. It should be noted, however,that the actual threshold value (or tolerance) may be applicationdependent. For example, in some embodiments, “approximately” may meanwithin 0.1% of some specified or desired value, while in various otherembodiments, the threshold may be, for example, 2%, 3%, 5%, and soforth, as desired or as required by the particular application.

Concurrent—refers to parallel execution or performance, where tasks,processes, or programs are performed in an at least partiallyoverlapping manner. For example, concurrency may be implemented using“strong” or strict parallelism, where tasks are performed (at leastpartially) in parallel on respective computational elements, or using“weak parallelism”, where the tasks are performed in an interleavedmanner, e.g., by time multiplexing of execution threads.

Configured to—Various components may be described as “configured to”perform a task or tasks. In such contexts, “configured to” is a broadrecitation generally meaning “having structure that” performs the taskor tasks during operation. As such, the component can be configured toperform the task even when the component is not currently performingthat task (e.g., a set of electrical conductors may be configured toelectrically connect a module to another module, even when the twomodules are not connected). In some contexts, “configured to” may be abroad recitation of structure generally meaning “having circuitry that”performs the task or tasks during operation. As such, the component canbe configured to perform the task even when the component is notcurrently on. In general, the circuitry that forms the structurecorresponding to “configured to” may include hardware circuits.

Various components may be described as performing a task or tasks, forconvenience in the description. Such descriptions should be interpretedas including the phrase “configured to.” Reciting a component that isconfigured to perform one or more tasks is expressly intended not toinvoke 35 U.S.C. § 112(f) interpretation for that component.

FIGS. 1 and 2—Communication System

FIG. 1 illustrates a simplified example wireless communication system,according to some embodiments. It is noted that the system of FIG. 1 ismerely one example of a possible system, and that features of thisdisclosure may be implemented in any of various systems, as desired.

As shown, the example wireless communication system includes a basestation 102A which communicates over a transmission medium with one ormore user devices 106A, 106B, etc., through 106N. Each of the userdevices may be referred to herein as a “user equipment” (UE). Thus, theuser devices 106 are referred to as UEs or UE devices.

The base station (BS) 102A may be a base transceiver station (BTS) orcell site (a “cellular base station”), and may include hardware thatenables wireless communication with the UEs 106A through 106N.

The communication area (or coverage area) of the base station may bereferred to as a “cell.” The base station 102A and the UEs 106 may beconfigured to communicate over the transmission medium using any ofvarious radio access technologies (RATs), also referred to as wirelesscommunication technologies, or telecommunication standards, such as GSM,UMTS (associated with, for example, WCDMA or TD-SCDMA air interfaces),LTE, LTE-Advanced (LTE-A), 5G new radio (5G NR), HSPA, 3GPP2 CDMA2000(e.g., 1×RTT, 1×EV-DO, HRPD, eHRPD), etc. Note that if the base station102A is implemented in the context of LTE, it may alternately bereferred to as an ‘eNodeB’ or ‘eNB’. Note that if the base station 102Ais implemented in the context of 5G NR, it may alternately be referredto as ‘gNodeB’ or ‘gNB’.

As shown, the base station 102A may also be equipped to communicate witha network 100 (e.g., a core network of a cellular service provider, atelecommunication network such as a public switched telephone network(PSTN), and/or the Internet, among various possibilities). Thus, thebase station 102A may facilitate communication between the user devicesand/or between the user devices and the network 100. In particular, thecellular base station 102A may provide UEs 106 with varioustelecommunication capabilities, such as voice, SMS and/or data services.

Base station 102A and other similar base stations (such as base stations102B . . . 102N) operating according to the same or a different cellularcommunication standard may thus be provided as a network of cells, whichmay provide continuous or nearly continuous overlapping service to UEs106A-N and similar devices over a geographic area via one or morecellular communication standards.

Thus, while base station 102A may act as a “serving cell” for UEs 106A-Nas illustrated in FIG. 1, each UE 106 may also be capable of receivingsignals from (and possibly within communication range of) one or moreother cells (which might be provided by base stations 102B-N and/or anyother base stations), which may be referred to as “neighboring cells”.Such cells may also be capable of facilitating communication betweenuser devices and/or between user devices and the network 100. Such cellsmay include “macro” cells, “micro” cells, “pico” cells, and/or cellswhich provide any of various other granularities of service area size.For example, base stations 102A-B illustrated in FIG. 1 might be macrocells, while base station 102N might be a micro cell. Otherconfigurations are also possible.

In some embodiments, base station 102A may be a next generation basestation, e.g., a 5G New Radio (5G NR) base station, or “gNB”. In someembodiments, a gNB may be connected to a legacy evolved packet core(EPC) network and/or to a NR core (NRC) network. In addition, a gNB cellmay include one or more transition and reception points (TRPs). Inaddition, a UE capable of operating according to 5G NR may be connectedto one or more TRPs within one or more gNBs. As another possibility,base station 102A may be a LTE base station, or “eNB”. In someembodiments, a eNB may be connected to a legacy evolved packet core(EPC) network and/or to a NR core (NRC) network.

Note that a UE 106 may be capable of communicating using multiplewireless communication standards. For example, the UE 106 may beconfigured to communicate using a wireless networking (e.g., Wi-Fi)and/or peer-to-peer wireless communication protocol (e.g., Bluetooth,Wi-Fi peer-to-peer, etc.) in addition to at least one cellularcommunication protocol (e.g., GSM, UMTS (associated with, for example,WCDMA or TD-SCDMA air interfaces), LTE, LTE-A, 5G NR, HSPA, 3GPP2CDMA2000 (e.g., 1×RTT, 1×EV-DO, HRPD, eHRPD), etc.). The UE 106 may alsoor alternatively be configured to communicate using one or more globalnavigational satellite systems (GNSS, e.g., GPS or GLONASS), one or moremobile television broadcasting standards (e.g., ATSC-M/H), and/or anyother wireless communication protocol, if desired. Other combinations ofwireless communication standards (including more than two wirelesscommunication standards) are also possible.

FIG. 2 illustrates user equipment 106 (e.g., one of the devices 106Athrough 106N) in communication with a base station 102, according tosome embodiments. The UE 106 may be a device with cellular communicationcapability such as a mobile phone, a hand-held device, a computer or atablet, or virtually any type of wireless device.

The UE 106 may include a processor (processing element) that isconfigured to execute program instructions stored in memory. The UE 106may perform any of the method embodiments described herein by executingsuch stored instructions. Alternatively, or in addition, the UE 106 mayinclude a programmable hardware element such as an FPGA(field-programmable gate array), an integrated circuit, and/or any ofvarious other possible hardware components that are configured toperform (e.g., individually or in combination) any of the methodembodiments described herein, or any portion of any of the methodembodiments described herein.

The UE 106 may include one or more antennas for communicating using oneor more wireless communication protocols or technologies. In someembodiments, the UE 106 may be configured to communicate using, forexample, CDMA2000 (1×RTT/1×EV-DO/HRPD/eHRPD) or LTE using a singleshared radio and/or GSM or LTE using the single shared radio. The sharedradio may couple to a single antenna, or may couple to multiple antennas(e.g., for MIMO) for performing wireless communications. In general, aradio may include any combination of a baseband processor, analog RFsignal processing circuitry (e.g., including filters, mixers,oscillators, amplifiers, etc.), or digital processing circuitry (e.g.,for digital modulation as well as other digital processing). Similarly,the radio may implement one or more receive and transmit chains usingthe aforementioned hardware. For example, the UE 106 may share one ormore parts of a receive and/or transmit chain between multiple wirelesscommunication technologies, such as those discussed above.

In some embodiments, the UE 106 may include separate transmit and/orreceive chains (e.g., including separate antennas and other radiocomponents) for each wireless communication protocol with which it isconfigured to communicate. As a further possibility, the UE 106 mayinclude one or more radios which are shared between multiple wirelesscommunication protocols, and one or more radios which are usedexclusively by a single wireless communication protocol. For example,the UE 106 might include a shared radio for communicating using eitherof LTE or 5G NR (or LTE or 1×RTT or LTE or GSM), and separate radios forcommunicating using each of Wi-Fi and Bluetooth. Other configurationsare also possible.

FIG. 3—Block Diagram of a UE

FIG. 3 illustrates an example simplified block diagram of acommunication device 106, according to some embodiments. It is notedthat the block diagram of the communication device of FIG. 3 is only oneexample of a possible communication device. According to embodiments,communication device 106 may be a user equipment (UE) device, a mobiledevice or mobile station, a wireless device or wireless station, adesktop computer or computing device, a mobile computing device (e.g., alaptop, notebook, or portable computing device), a tablet and/or acombination of devices, among other devices. As shown, the communicationdevice 106 may include a set of components 300 configured to performcore functions. For example, this set of components may be implementedas a system on chip (SOC), which may include portions for variouspurposes. Alternatively, this set of components 300 may be implementedas separate components or groups of components for the various purposes.The set of components 300 may be coupled (e.g., communicatively;directly or indirectly) to various other circuits of the communicationdevice 106.

For example, the communication device 106 may include various types ofmemory (e.g., including NAND flash 310), an input/output interface suchas connector I/F 320 (e.g., for connecting to a computer system; dock;charging station; input devices, such as a microphone, camera, keyboard;output devices, such as speakers; etc.), the display 360, which may beintegrated with or external to the communication device 106, andcellular communication circuitry 330 such as for 5G NR, LTE, GSM, etc.,and short to medium range wireless communication circuitry 329 (e.g.,Bluetooth™ and WLAN circuitry). In some embodiments, communicationdevice 106 may include wired communication circuitry (not shown), suchas a network interface card, e.g., for Ethernet.

The cellular communication circuitry 330 may couple (e.g.,communicatively; directly or indirectly) to one or more antennas, suchas antennas 335 and 336 as shown. The short to medium range wirelesscommunication circuitry 329 may also couple (e.g., communicatively;directly or indirectly) to one or more antennas, such as antennas 337and 338 as shown. Alternatively, the short to medium range wirelesscommunication circuitry 329 may couple (e.g., communicatively; directlyor indirectly) to the antennas 335 and 336 in addition to, or insteadof, coupling (e.g., communicatively; directly or indirectly) to theantennas 337 and 338. The short to medium range wireless communicationcircuitry 329 and/or cellular communication circuitry 330 may includemultiple receive chains and/or multiple transmit chains for receivingand/or transmitting multiple spatial streams, such as in amultiple-input multiple output (MIMO) configuration.

In some embodiments, as further described below, cellular communicationcircuitry 330 may include dedicated receive chains (including and/orcoupled to, e.g., communicatively; directly or indirectly. dedicatedprocessors and/or radios) for multiple RATs (e.g., a first receive chainfor LTE and a second receive chain for 5G NR). In addition, in someembodiments, cellular communication circuitry 330 may include a singletransmit chain that may be switched between radios dedicated to specificRATs. For example, a first radio may be dedicated to a first RAT, e.g.,LTE, and may be in communication with a dedicated receive chain and atransmit chain shared with an additional radio, e.g., a second radiothat may be dedicated to a second RAT, e.g., 5G NR, and may be incommunication with a dedicated receive chain and the shared transmitchain.

The communication device 106 may also include and/or be configured foruse with one or more user interface elements. The user interfaceelements may include any of various elements, such as display 360 (whichmay be a touchscreen display), a keyboard (which may be a discretekeyboard or may be implemented as part of a touchscreen display), amouse, a microphone and/or speakers, one or more cameras, one or morebuttons, and/or any of various other elements capable of providinginformation to a user and/or receiving or interpreting user input.

The communication device 106 may further include one or more smart cards345 that include SIM (Subscriber Identity Module) functionality, such asone or more UICC(s) (Universal Integrated Circuit Card(s)) cards 345.

As shown, the SOC 300 may include processor(s) 302, which may executeprogram instructions for the communication device 106 and displaycircuitry 304, which may perform graphics processing and provide displaysignals to the display 360. The processor(s) 302 may also be coupled tomemory management unit (MMU) 340, which may be configured to receiveaddresses from the processor(s) 302 and translate those addresses tolocations in memory (e.g., memory 306, read only memory (ROM) 350, NANDflash memory 310) and/or to other circuits or devices, such as thedisplay circuitry 304, short range wireless communication circuitry 229,cellular communication circuitry 330, connector I/F 320, and/or display360. The MMU 340 may be configured to perform memory protection and pagetable translation or set up. In some embodiments, the MMU 340 may beincluded as a portion of the processor(s) 302.

As noted above, the communication device 106 may be configured tocommunicate using wireless and/or wired communication circuitry. Thecommunication device 106 may be configured to transmit a request toattach to a first network node operating according to the first RAT andtransmit an indication that the wireless device is capable ofmaintaining substantially concurrent connections with the first networknode and a second network node that operates according to the second RAT(or that also operates according to the first RAT). The wireless devicemay also be configured transmit a request to attach to the secondnetwork node. The request may include an indication that the wirelessdevice is capable of maintaining substantially concurrent connectionswith the first and second network nodes. Further, the wireless devicemay be configured to receive an indication that dual connectivity withthe first and second network nodes has been established.

As described herein, the communication device 106 may include hardwareand software components for implementing features for performing mastercell group failure recovery in a dual connectivity cellularcommunication system, as well as the various other techniques describedherein. The processor 302 of the communication device 106 may beconfigured to implement part or all of the features described herein,e.g., by executing program instructions stored on a memory medium (e.g.,a non-transitory computer-readable memory medium). Alternatively (or inaddition), processor 302 may be configured as a programmable hardwareelement, such as an FPGA (Field Programmable Gate Array), or as an ASIC(Application Specific Integrated Circuit). Alternatively (or inaddition) the processor 302 of the communication device 106, inconjunction with one or more of the other components 300, 304, 306, 310,320, 329, 330, 335, 336, 337, 338, 340, 345, 350, 360 may be configuredto implement part or all of the features described herein.

In addition, as described herein, processor 302 may include one or moreprocessing elements. Thus, processor 302 may include one or moreintegrated circuits (ICs) that are configured to perform the functionsof processor 302. In addition, each integrated circuit may includecircuitry (e.g., first circuitry, second circuitry, etc.) configured toperform the functions of processor(s) 302.

Further, as described herein, cellular communication circuitry 330 andshort range wireless communication circuitry 329 may each include one ormore processing elements. In other words, one or more processingelements may be included in cellular communication circuitry 330 and,similarly, one or more processing elements may be included in shortrange wireless communication circuitry 329. Thus, cellular communicationcircuitry 330 may include one or more integrated circuits (ICs) that areconfigured to perform the functions of cellular communication circuitry330. In addition, each integrated circuit may include circuitry (e.g.,first circuitry, second circuitry, etc.) configured to perform thefunctions of cellular communication circuitry 230. Similarly, the shortrange wireless communication circuitry 329 may include one or more ICsthat are configured to perform the functions of short range wirelesscommunication circuitry 32. In addition, each integrated circuit mayinclude circuitry (e.g., first circuitry, second circuitry, etc.)configured to perform the functions of short range wirelesscommunication circuitry 329.

FIG. 4—Block Diagram of a Base Station

FIG. 4 illustrates an example block diagram of a base station 102,according to some embodiments. It is noted that the base station of FIG.4 is merely one example of a possible base station. As shown, the basestation 102 may include processor(s) 404 which may execute programinstructions for the base station 102. The processor(s) 404 may also becoupled to memory management unit (MMU) 440, which may be configured toreceive addresses from the processor(s) 404 and translate thoseaddresses to locations in memory (e.g., memory 460 and read only memory(ROM) 450) or to other circuits or devices.

The base station 102 may include at least one network port 470. Thenetwork port 470 may be configured to couple to a telephone network andprovide a plurality of devices, such as UE devices 106, access to thetelephone network as described above in FIGS. 1 and 2.

The network port 470 (or an additional network port) may also oralternatively be configured to couple to a cellular network, e.g., acore network of a cellular service provider. The core network mayprovide mobility related services and/or other services to a pluralityof devices, such as UE devices 106. In some cases, the network port 470may couple to a telephone network via the core network, and/or the corenetwork may provide a telephone network (e.g., among other UE devicesserviced by the cellular service provider).

In some embodiments, base station 102 may be a next generation basestation, e.g., a 5G New Radio (5G NR) base station, or “gNB”. In suchembodiments, base station 102 may be connected to a legacy evolvedpacket core (EPC) network and/or to a NR core (NRC) network. Inaddition, base station 102 may be considered a 5G NR cell and mayinclude one or more transition and reception points (TRPs). In addition,a UE capable of operating according to 5G NR may be connected to one ormore TRPs within one or more gNB s.

The base station 102 may include at least one antenna 434, and possiblymultiple antennas. The antenna(s) 434 may be configured to operate as awireless transceiver and may be further configured to communicate withUE devices 106 via radio 430. The antenna(s) 434 communicates with theradio 430 via communication chain 432. Communication chain 432 may be areceive chain, a transmit chain or both. The radio 430 may be configuredto communicate via various wireless communication standards, including,but not limited to, 5G NR, LTE, LTE-A, GSM, UMTS, CDMA2000, Wi-Fi, etc.

The base station 102 may be configured to communicate wirelessly usingmultiple wireless communication standards. In some instances, the basestation 102 may include multiple radios, which may enable the basestation 102 to communicate according to multiple wireless communicationtechnologies. For example, as one possibility, the base station 102 mayinclude an LTE radio for performing communication according to LTE aswell as a 5G NR radio for performing communication according to 5G NR.In such a case, the base station 102 may be capable of operating as bothan LTE base station and a 5G NR base station. As another possibility,the base station 102 may include a multi-mode radio which is capable ofperforming communications according to any of multiple wirelesscommunication technologies (e.g., 5G NR and LTE, 5G NR and Wi-Fi, LTEand Wi-Fi, LTE and UMTS, LTE and CDMA2000, UMTS and GSM, etc.).

As described further subsequently herein, the BS 102 may includehardware and software components for implementing or supportingimplementation of features described herein. The processor 404 of thebase station 102 may be configured to implement or supportimplementation of part or all of the methods described herein, e.g., byexecuting program instructions stored on a memory medium (e.g., anon-transitory computer-readable memory medium). Alternatively, theprocessor 404 may be configured as a programmable hardware element, suchas an FPGA (Field Programmable Gate Array), or as an ASIC (ApplicationSpecific Integrated Circuit), or a combination thereof. Alternatively(or in addition) the processor 404 of the BS 102, in conjunction withone or more of the other components 430, 432, 434, 440, 450, 460, 470may be configured to implement or support implementation of part or allof the features described herein.

In addition, as described herein, processor(s) 404 may include one ormore processing elements. Thus, processor(s) 404 may include one or moreintegrated circuits (ICs) that are configured to perform the functionsof processor(s) 404. In addition, each integrated circuit may includecircuitry (e.g., first circuitry, second circuitry, etc.) configured toperform the functions of processor(s) 404.

Further, as described herein, radio 430 may include one or moreprocessing elements. Thus, radio 430 may include one or more integratedcircuits (ICs) that are configured to perform the functions of radio430. In addition, each integrated circuit may include circuitry (e.g.,first circuitry, second circuitry, etc.) configured to perform thefunctions of radio 430.

FIG. 5—Block Diagram of Cellular Communication Circuitry

FIG. 5 illustrates an example simplified block diagram of cellularcommunication circuitry, according to some embodiments. It is noted thatthe block diagram of the cellular communication circuitry of FIG. 5 isonly one example of a possible cellular communication circuit; othercircuits, such as circuits including or coupled to sufficient antennasfor different RATs to perform uplink activities using separate antennas,are also possible. According to some embodiments, cellular communicationcircuitry 330 may be included in a communication device, such ascommunication device 106 described above herein. As noted above herein,communication device 106 may be a user equipment (UE) device, a mobiledevice or mobile station, a wireless device or wireless station, adesktop computer or computing device, a mobile computing device (e.g., alaptop, notebook, or portable computing device), a wearable device, atablet and/or a combination of devices, among other devices.

The cellular communication circuitry 330 may couple (e.g.,communicatively; directly or indirectly) to one or more antennas, suchas antennas 335 a-b and 336 as shown. In some embodiments, cellularcommunication circuitry 330 may include dedicated receive chains(including and/or coupled to, e.g., communicatively; directly orindirectly), dedicated processors, and/or radios for multiple RATs(e.g., a first receive chain for LTE and a second receive chain for 5GNR). For example, as shown in FIG. 5, cellular communication circuitry330 may include a modem 510 and a modem 520. Modem 510 may be configuredfor communications according to a first RAT, such as LTE or LTE-A, andmodem 520 may be configured for communications according to a secondRAT, such as 5G NR.

As shown, modem 510 may include one or more processors 512 and a memory516 in communication with processors 512. Modem 510 may be incommunication with a radio frequency (RF) front end 530. RF front end530 may include circuitry for transmitting and receiving radio signals.For example, RF front end 530 may include receive circuitry (RX) 532 andtransmit circuitry (TX) 534. In some embodiments, receive circuitry 532may be in communication with downlink (DL) front end 550, which mayinclude circuitry for receiving radio signals via antenna 335 a.

Similarly, modem 520 may include one or more processors 522 and a memory526 in communication with processors 522. Modem 520 may be incommunication with an RF front end 540. RF front end 540 may includecircuitry for transmitting and receiving radio signals. For example, RFfront end 540 may include receive circuitry 542 and transmit circuitry544. In some embodiments, receive circuitry 542 may be in communicationwith DL front end 560, which may include circuitry for receiving radiosignals via antenna 335 b.

In some embodiments, a switch 570 may couple transmit circuitry 534 touplink (UL) front end 572. In addition, switch 570 may couple transmitcircuitry 544 to UL front end 572. UL front end 572 may includecircuitry for transmitting radio signals via antenna 336. Thus, whencellular communication circuitry 330 receives instructions to transmitaccording to the first RAT (e.g., as supported via modem 510), switch570 may be switched to a first state that allows modem 510 to transmitsignals according to the first RAT (e.g., via a transmit chain thatincludes transmit circuitry 534 and UL front end 572). Similarly, whencellular communication circuitry 330 receives instructions to transmitaccording to the second RAT (e.g., as supported via modem 520), switch570 may be switched to a second state that allows modem 520 to transmitsignals according to the second RAT (e.g., via a transmit chain thatincludes transmit circuitry 544 and UL front end 572).

In some embodiments, the cellular communication circuitry 330 may beconfigured to transmit, via the first modem while the switch is in thefirst state, a request to attach to a first network node operatingaccording to the first RAT and transmit, via the first modem while theswitch is in a first state, an indication that the wireless device iscapable of maintaining substantially concurrent connections with thefirst network node and a second network node that operates according tothe second RAT. The wireless device may also be configured transmit, viathe second radio while the switch is in a second state, a request toattach to the second network node. The request may include an indicationthat the wireless device is capable of maintaining substantiallyconcurrent connections with the first and second network nodes. Further,the wireless device may be configured to receive, via the first radio,an indication that dual connectivity with the first and second networknodes has been established.

As described herein, the modem 510 may include hardware and softwarecomponents for implementing features for performing master cell groupfailure recovery in a dual connectivity cellular communication system,as well as the various other techniques described herein. The processors512 may be configured to implement part or all of the features describedherein, e.g., by executing program instructions stored on a memorymedium (e.g., a non-transitory computer-readable memory medium).

Alternatively (or in addition), processor 512 may be configured as aprogrammable hardware element, such as an FPGA (Field Programmable GateArray), or as an ASIC (Application Specific Integrated Circuit).Alternatively (or in addition) the processor 512, in conjunction withone or more of the other components 530, 532, 534, 550, 570, 572, 335and 336 may be configured to implement part or all of the featuresdescribed herein.

In addition, as described herein, processors 512 may include one or moreprocessing elements. Thus, processors 512 may include one or moreintegrated circuits (ICs) that are configured to perform the functionsof processors 512. In addition, each integrated circuit may includecircuitry (e.g., first circuitry, second circuitry, etc.) configured toperform the functions of processors 512.

As described herein, the modem 520 may include hardware and softwarecomponents for implementing features for performing master cell groupfailure recovery in a dual connectivity cellular communication system,as well as the various other techniques described herein. The processors522 may be configured to implement part or all of the features describedherein, e.g., by executing program instructions stored on a memorymedium (e.g., a non-transitory computer-readable memory medium).Alternatively (or in addition), processor 522 may be configured as aprogrammable hardware element, such as an FPGA (Field Programmable GateArray), or as an ASIC (Application Specific Integrated Circuit).Alternatively (or in addition) the processor 522, in conjunction withone or more of the other components 540, 542, 544, 550, 570, 572, 335and 336 may be configured to implement part or all of the featuresdescribed herein.

In addition, as described herein, processors 522 may include one or moreprocessing elements. Thus, processors 522 may include one or moreintegrated circuits (ICs) that are configured to perform the functionsof processors 522. In addition, each integrated circuit may includecircuitry (e.g., first circuitry, second circuitry, etc.) configured toperform the functions of processors 522.

FIGS. 6A-6B—5G NR Non-Standalone (NSA) Architecture with LTE

In some implementations, fifth generation (5G) wireless communicationwill initially be deployed concurrently with current wirelesscommunication standards (e.g., LTE). For example, dual connectivitybetween LTE and 5G new radio (5G NR or NR) has been specified as part ofthe initial deployment of NR. Thus, as illustrated in FIGS. 6A-B,evolved packet core (EPC) network 600 may continue to communicate withcurrent LTE base stations (e.g., eNB 602). In addition, eNB 602 may bein communication with a 5G NR base station (e.g., gNB 604) and may passdata between the EPC network 600 and gNB 604. Thus, EPC network 600 maybe used (or reused) and gNB 604 may serve as extra capacity for UEs,e.g., for providing increased downlink throughput to UEs. In otherwords, LTE may be used for control plane signaling and NR may be usedfor user plane signaling. Thus, LTE may be used to establish connectionsto the network and NR may be used for data services.

FIG. 6B illustrates a proposed protocol stack for eNB 602 and gNB 604.As shown, eNB 602 may include a medium access control (MAC) layer 632that interfaces with radio link control (RLC) layers 622 a-b. RLC layer622 a may also interface with packet data convergence protocol (PDCP)layer 612 a and RLC layer 622 b may interface with PDCP layer 612 b.Similar to dual connectivity as specified in LTE-Advanced Release 12,PDCP layer 612 a may interface via a master cell group (MCG) bearer toEPC network 600 whereas PDCP layer 612 b may interface via a splitbearer with EPC network 600.

Additionally, as shown, gNB 604 may include a MAC layer 634 thatinterfaces with RLC layers 624 a-b. RLC layer 624 a may interface withPDCP layer 612 b of eNB 602 via an X2 interface for information exchangeand/or coordination (e.g., scheduling of a UE) between eNB 602 and gNB604. In addition, RLC layer 624 b may interface with PDCP layer 614.Similar to dual connectivity as specified in LTE-Advanced Release 12,PDCP layer 614 may interface with EPC network 600 via a secondary cellgroup (SCG) bearer. Thus, eNB 602 may be considered a master node (MeNB)while gNB 604 may be considered a secondary node (SgNB). In somescenarios, a UE may be required to maintain a connection to both an MeNBand a SgNB. In such scenarios, the MeNB may be used to maintain a radioresource control (RRC) connection to an EPC while the SgNB may be usedfor capacity (e.g., additional downlink and/or uplink throughput).

Thus, FIGS. 6A-6B may represent aspects of one possible cellularcommunication system that implements dual connectivity. However, itshould be noted that numerous other dual (or more generally multiple)connectivity configurations are also possible, and that features of thisdisclosure can be implemented any of a variety of such configurations.Some other examples could include a configuration in which a gNB can beconfigured as a master node and a eNB can be configured as a secondarynode, or a configuration in which both a master node and a secondarynode operate according to the same RAT (e.g., both operate according toNR, both operate according to LTE, etc.), among various other possibleconfigurations.

FIG. 7—Master Cell Group Failure Recovery

FIG. 7 is a flowchart diagram illustrating an example method for awireless device to perform master cell group failure recovery in a dualconnectivity cellular communication system, according to someembodiments. Aspects of the method of FIG. 7 may be implemented by awireless device such as a UE 106 illustrated in various of the Figuresherein, or more generally in conjunction with any of the computercircuitry, systems, devices, elements, or components shown in the aboveFigures, among others, as desired. For example, a processor (and/orother hardware) of such a device may be configured to cause the deviceto perform any combination of the illustrated method elements and/orother method elements.

In various embodiments, some of the elements of the method shown may beperformed concurrently, in a different order than shown, may besubstituted for by other method elements, or may be omitted. Additionalelements may also be performed as desired. As shown, the method mayoperate as follows.

At 702, the wireless device may establish cellular links with a firstcell group (which may be configured as a master cell group (MCG)) and asecond cell group (which may be configured as a secondary cell group(SCG)), e.g., to obtain dual connectivity with a cellular network. Thismay include attaching to and establishing a radio resource controlconnection with a first base station that operates according to a firstRAT, which may provide a first cell (or group of cells) operating in afirst system bandwidth (e.g., including a first carrier frequency). Thismay further include attaching to and establishing a radio resourcecontrol connection with a second base station that operates according tothe second RAT (or also operates according to the first RAT), which mayprovide a second cell (or group of cells) operating in a second systembandwidth (e.g., including a second carrier frequency), which maypossibly be different than the first system bandwidth. Note that thefirst base station and the second base station may be different physicalbase stations or may be provided by the same physical base station andmay differ only logically (e.g., a base station may be capable ofproviding cells according to both the first RAT and the second RAT).

In some embodiments, one of the RATs may be LTE and the other RAT may beNR; for example, the first RAT may be LTE and the second RAT may be NR,or the first RAT may be NR and the second RAT may be LTE. The order inwhich the cellular links are established may be arbitrary or may dependon any of various considerations, potentially including networkarchitecture (e.g., if one of the base stations is intended for NSAoperation and/or is a secondary base station), relative signal strength,relative priority level, etc. As one possibility, the wireless devicemay initially transmit signaling to an LTE base station, such as eNB 602described previously herein, to establish an attachment to an LTEnetwork. In other words, the wireless device may request a connectionwith the LTE base station. Similarly, in some instances, the wirelessdevice may transmit signaling to a 5G NR base station, such as gNB 604described previously herein, to establish an attachment to a 5G NRnetwork. In other words, the wireless device may request a connectionwith the 5G NR base station.

Note that such an approach to establishing dual connectivity is onepossibility among numerous other possible mechanisms and procedures forestablishing dual connectivity with the MCG and the SCG. For example, asanother possibility, as previously noted, it may also be possible thatthe MCG and the SCG operate according to the same RAT (e.g., both NR).Generally, the cellular links with the MCG and the SCG may be configuredin accordance with any of various possible multi-RAT dual connectivity(MR-DC) configurations.

In 704, the wireless device may determine that it is experiencing MCGlink failure (e.g., that link failure of the cellular link with the MCGhas occurred). The MCG link failure may include any of various types oflink failure. For example, the MCG link failure may be a radio linkfailure (RLF), which the wireless device may determine to have occurredbased at least in part on any or all of a random access channel (RACH)procedure failure, a radio link control (RLC) failure, a radio linkmonitoring (RLM) failure, and/or any of various other causes.

In 706, the wireless device may perform MCG link failure recovery usingthe cellular link with the SCG. This may include suspending MCGtransmission and reception and providing MCG link failure information tothe cellular network using the cellular link with the SCG. The MCG linkfailure information can include any of various types of information. Asone possibility, the MCG link failure information may include causeinformation for the MCG link failure. For example, as previously noted,the wireless device may have determined whether the MCG RLF occurred asa result of RACH failure, RLC failure, RLM failure, etc., and mayprovide such cause information as part of the MCG link failureinformation.

As another possibility, the MCG link failure information may includecell measurement information for the MCG and/or one or more other cells.For example, the wireless device may perform one or more serving celland/or neighboring cell measurements based at least in part ondetermining that the wireless device is experiencing MCG link failure,and the MCG link failure information may include results of such cellmeasurements. Such information may assist the cellular network withdetermining how best to approach MCG link failure recovery.

At least according to some embodiments, the SCG may provide anindication that the wireless device is experiencing MCG link failure tothe MCG. The indication may include the MCG link failure informationprovided by the wireless device. The indication may be provided in anyof various manners, e.g., potentially depending on a signaling radiobearer (SRB) configuration of the wireless device, the MCG, and the SCG,and a SRB used by the wireless device to provide the indication that thewireless device is experiencing MCG link failure. For example, as onepossibility, the wireless device may provide the indication that thewireless device is experiencing MCG link failure using a SRB that issplit between the MCG and the SCG, and the SCG may also use the SRB thatis split between the MCG and the SCG to forward the indication that thewireless device is experiencing MCG link failure. As anotherpossibility, the wireless device may provide the indication that thewireless device is experiencing MCG link failure using a SRB that isspecific to the wireless link between the wireless device and the SCG.In some instances, such an indication may be included as a containerwithin a message provided using a format of the SRB that is specific tothe wireless link between the wireless device and the SCG. In such acase, the SCG may use a SRB that is split between the MCG and the SCG toforward the indication that the wireless device is experiencing MCG linkfailure. As another possibility, the SCG may use an X2 message toforward the indication that the wireless device is experiencing MCG linkfailure.

The SCG may receive MCG reconfiguration information for the wirelessdevice from the MCG, e.g., based on the MCG link failure informationindicating that the wireless device is experiencing MCG link failure.The MCG reconfiguration information for the wireless device couldinclude reconfiguration information modifying one or more of cellfrequency, band, or resource configuration information (among variouspossibilities) for the primary cell of the wireless device, e.g., topotentially allow for the wireless device to recover the cellular linkwith the first cell group. For example, the MCG reconfigurationinformation could include an indication to perform handover to adifferent primary cell provided by the first cell group. As anotherpossibility, the MCG reconfiguration information could include anindication to continue to use the current primary cell, but to use adifferent resource configuration. The SCG may provide such MCGreconfiguration information to the wireless device via the cellular linkbetween the SCG and the wireless device, e.g., using the same signalingmechanism by which the MCG link failure information was received. Thewireless device may accordingly receive the MCG reconfigurationinformation via the selected signaling mechanism on the cellular linkbetween the wireless device and the SCG. In such a case, the wirelessdevice may perform MCG reconfiguration in accordance with the MCGreconfiguration information and resume MCG transmission and receptionwith the first cell group continuing to act as MCG for the wirelessdevice.

As another possibility, the MCG may determine to handover the primarycell (and thus MCG) of the wireless device to the second cell group, forexample based on cell measurement information, network loadconsiderations, and/or for any of various other reasons. In such a case,the second cell group may receive a request from the first cell group tohandover MCG for the wireless device to the second cell group. Thesecond cell group may respond to the first cell group with aconfirmation to handover MCG for the wireless device to the second cellgroup. The second cell group may further determine MCG reconfigurationinformation (e.g., indicating to handover to a primary cell provided bythe second cell group, among various possible information) for thewireless device, and provide the MCG reconfiguration information to thewireless device using the cellular link between the second cell groupand the wireless device.

According to some embodiments, the wireless device may initiate a MCGrecovery timer in conjunction with determining that the wireless deviceis experiencing MCG link failure and/or attempting to perform MCG linkfailure recover via the SCG. For example, it may be preferable to limitthe amount of time that the wireless device spends attempting to performMCG link failure recovery via the SCG, in case such MCG link failurerecovery efforts are unsuccessful, before attempting an alternativeapproach MCG link failure recovery. Thus, the MCG recovery timer may beinitiated upon transmitting the MCG link failure information to the SCG,or possibly alternatively upon determining that link failure with theMCG has occurred. In such a case, if MCG link failure recovery has notyet succeeded when the MCG recovery timer expires, the wireless devicemay stop performing MCG link failure recovery via the SCG. The wirelessdevice may, for example, initiate a radio resource controlre-establishment procedure if the MCG recovery timer expires. Noteadditionally that if the wireless device also experiences SCG linkfailure while experiencing MCG link failure, the wireless device maysimilarly stop performing MCG link failure recovery via the SCG and mayinitiate a radio resource control re-establishment procedure.

Note that while such MCG link failure recovery is being performed, thewireless device and the cellular network may be able to continue toperform uplink and/or downlink data transmissions, e.g., via thecellular link between the wireless device and the SCG. In other words,using the techniques described herein for MCG link failure recoveryusing a SCG, it may be possible to continue data activity withoutinterruption when MCG link failure occurs, at least in some instances.

Note that while the techniques for performing master cell group failurerecovery in a dual connectivity cellular communication system describedwith respect to FIG. 7 are described primarily in conjunction withactivities by a wireless device, similar techniques may be used, e.g.,by a cellular base station, to handle or facilitate such failurerecovery on the network side, if desired.

FIGS. 8-19 and Additional Information

FIGS. 8-19 and the following additional information are provided by wayof example of various considerations and details relating to possiblesystems in which the method of FIG. 7 and/or other aspects of thisdisclosure may be implemented, and are not intended to be limiting tothe disclosure as a whole. Numerous variations and alternatives to thedetails provided herein below are possible and should be consideredwithin the scope of the disclosure.

FIG. 8 illustrates aspects of an exemplary possible dual connectivitycellular communication system. As shown, a UE 806 may be incommunication with a master cell group 802 and a secondary cell group804. As shown, possible signaling radio bearers for the communicationsystem could include SRB1 and SRB2, which may be used to communicatewith the MCG, and possibly also with the SCG in a split bearerconfiguration. The possible signaling radio bearers for thecommunication system could also or alternatively include SRB3, which maybe a SCG specific SRB.

FIG. 9 is a signal flow diagram illustrating an exemplary scenario inwhich a split SRB configuration is used. As shown, a UE 906 may performuplink and downlink signaling via a split SRB with a secondary node (SN)904 and a master node (MN) 902. The split SRB configuration may beapplicable to MCG SRBs (e.g., MCG SRB1/MCG SRB2). For such SRBs,transmission can be via the MCG or the SCG. In the network, the MN 902may be used for RRC message encoding/decoding.

FIG. 10 is a signal flow diagram illustrating an exemplary scenario inwhich a SCG specific SRB configuration is used. As shown, a UE 1006 mayperform uplink and downlink signaling with a SN 1004, and may separatelybe in communication with a MN 1002 (not shown). The SCG SRB (e.g., SCGSRB3) may be used to provide SN RRC reconfiguration messages, SN RRCreconfiguration complete messages, SN measurement report messages,and/or other RRC messages. For such a SRB, transmission may be performedvia SCG (e.g., only). In the network, the SN 1004 may be used for RRCmessage encoding/decoding.

At least according to some embodiments, RLF may be declared separatelyfor the MCG and for the SCG in such a dual connectivity cellularcommunication system. As one possible approach to handling RLF on theMCG, a UE may initiate a RRC connection re-establishment procedure. FIG.11 illustrates aspects of such an exemplary approach. As shown, in 1108,a UE 1106 may be configured in dual connectivity mode with a MN 1102 anda SN 1104. Thus, the UE 1106 may be able to communicate with the MN1102, and the SN 1104, and the MN 1102 and the SN 1104 may communicatewith each other (e.g., via an X2 interface, or in another manner). In1110, the UE 1106 may detect MCG failure, as RLF may be declared withthe MN 1102, although the wireless link between the UE 1106 and the SN1104, as well as the link between MN 1102 and SN 1104, may remainconnected. Based on the MCG failure, the UE 1106 may stop all datareception and transmission on both the MCG and the SCG, select a newcandidate serving cell, and trigger UE connection re-establishment. In1112, the UE 1106 may then perform UE connection re-establishment (e.g.,with the MN 1102, or with whatever node provides the selected candidateserving cell).

However, if there is no problem with the SCG, it may alternatively bepossible to recover the MCG problem via the SCG, potentially avoidinginterruption of data communication (e.g., since data communication withthe SCG can continue even while the MCG failure is occurring). Further,it may also potentially be possible to avoid UE connectionre-establishment handling by recovering the MCG problem via the SCG,which may potentially reduce UE power consumption and/or reduce networksignaling burden, among various possible benefits.

Thus, according to such an approach, if only MCG failure is detected(e.g., if the SCG link still works), a UE may initiate a MCG failurerecovery procedure via a SCG path. The MCG failure recovery proceduremay include suspending MCG transmission/reception, and possibly (e.g.,optionally) performing one or more cell measurements on the MCG servingcell. The UE may transmit MCG failure information to the network via theSN providing the SCG, and the SN may forward the information to the MNproviding the MCG. The MCG failure information could include failurecause information, any serving cell measurement results, and/or anyadditional (e.g., neighbor/alternative cell measurement results. The MCGfailure information could be transmitted on a split SRB (e.g., the SCGleg of a split SRB1), or on a SCG specific SRB (e.g., SRB3).

Based on the MCG failure information, the MN may adjust the MCGconfiguration (e.g., may determine MCG reconfiguration information,which may or may not include a primary cell (PCell) change), andtransmit RRC reconfiguration information with the adjusted MCGconfiguration to the UE via the SCG path.

Upon receiving the first reconfiguration after MCG failure detection,the UE may apply the configuration, resume the MCGtransmission/reception, and may send a RRC reconfiguration completemessage to the network, e.g., via the target PCell. If the firstreconfiguration complete transmission is successful, the MCG failure maybe successfully recovered.

As previously noted herein, it may be the case that data transmission onthe SCG is not impacted during such a MCG recovery procedure, at leastaccording to some embodiments.

The UE may also initiate a MCG recovery timer in conjunction with theMCG failure recovery procedure via the SCG path. For example, such atimer may be initiated when the UE transmits the MCG failure informationto the network. If the MCG failure recovery via the SCG path issuccessful, the MCG recovery timer may be stopped. However, if the MCGrecovery timer expires (e.g., and the MCG failure is still occurring),the UE may stop all transmissions and initiate UE connectionre-establishment. Similarly, if SCG failure is detected after the MCGfailure recovery procedure via the SCG path is initiated, or if SCGfailure is detected together with MCG failure, the UE may also initiatean RRC connection re-establishment procedure.

FIGS. 12-19 are signal flow diagrams illustrating various possiblescenarios in which such a MCG failure recovery procedure may beattempted via a SCG path. FIG. 12 illustrates a scenario in which MCGfailure recovery is performed via a split SRB (e.g., SRB1). As shown, in1208, a UE 1206, MN 1202, and SN 1204 may be configured to communicatein dual connectivity mode. In 1210, the UE 1206 may determine that MCGlink failure has occurred, but that the SCG link remains connected, andmay initiate a MCG failure recovery procedure, including suspending MCGtransmission, continuing SCG data transmission, and transmitting MCGfailure information on the SRB1. In 1212, the SN 1204 may receive theMCG failure information via the SRB1, and may forward the SRB1 data(e.g., including the MCG failure information) to the MN 1202. In 1214,based on the MCG failure information, the MN 1202 may determine not tochange the PCell for the UE 1206, but to adjust the PCell configurationfor the UE 1206. The MN 1202 may provide RRC reconfiguration informationindicating this adjustment to the SN 1204, which may in turn provide theRRC reconfiguration information to the UE 1206, e.g., using the SCG legof the SRB1. In 1216, the UE 1206 may receive the RRC reconfigurationmessage, and may apply the indicated PCell configuration, resume MCGtransmission (possibly only on the PCell, with the Scell in adeactivated state), and transmit a RRC reconfiguration complete messageto the MN 1202.

FIG. 13 illustrates a scenario in which MCG failure recovery isperformed via a SCG specific SRB (e.g., SRB3). As shown, in 1308, a UE1306, MN 1302, and SN 1304 may be configured to communicate in dualconnectivity mode. In 1310, the UE 1306 may determine that MCG linkfailure has occurred, but that the SCG link remains connected, and mayinitiate a MCG failure recovery procedure, including suspending MCGtransmission, continuing SCG data transmission, and transmitting MCGfailure information on the SRB3. The MCG failure information may betransmitted using a RRC message format 1320 that includes a SRB1container within the SRB3 RRC message, as shown. In 1312, the SN 1304may receive the MCG failure information via the SRB3, and may forwardthe SRB1 container (e.g., including the MCG failure information) to theMN 1302. In 1314, based on the MCG failure information, the MN 1302 maydetermine to change the PCell for the UE 1306, but keep the PCell withthe MN 1302. The MN 1302 may provide RRC reconfiguration informationindicating this adjustment to the SN 1304, which may in turn provide theRRC reconfiguration information to the UE 1306, e.g., using a similarSRB1 container for the RRC reconfiguration information within a SRB3 RRCmessage. In 1316, the UE 1306 may receive the RRC reconfigurationmessage, and may apply the indicated PCell configuration, transmit a RRCreconfiguration complete message to the MN 1302, and resume MCGtransmission. Note that it may be the case that both MCG and SCGtransmission is stopped during the handover to the new PCell.

FIG. 14 illustrates an alternate scenario in which MCG failure recoveryis performed via a SCG specific SRB (e.g., SRB3). As shown, in 1408, aUE 1406, MN 1402, and SN 1404 may be configured to communicate in dualconnectivity mode. In 1410, the UE 1406 may determine that MCG linkfailure has occurred, but that the SCG link remains connected, and mayinitiate a MCG failure recovery procedure, including suspending MCGtransmission, continuing SCG data transmission, and transmitting MCGfailure information on the SRB3. The MCG failure information may betransmitted using a RRC message format 1420 that includes a SRB1container within the SRB3 RRC message, as shown. In 1412, the SN 1404may receive the MCG failure information via the SRB3, and may forwardthe MCG failure information included in the SRB1 container to the MN1402 via X2 messgae. In 1414, based on the MCG failure information, theMN 1402 may determine to change the PCell for the UE 1406, but keep thePCell with the MN 1402. The MN 1402 may provide RRC reconfigurationinformation indicating this adjustment to the SN 1404 (e.g., again viaX2 message). In 1416, the SN 1404 may assemble a SRB3 reconfigurationmessage, which may include the RRC reconfiguration information in a SRB1container, and may provide the SRB3 reconfiguration message to the UE1406. In 1418, the UE 1406 may receive the RRC reconfiguration message,and may apply the indicated PCell configuration, transmit a RRCreconfiguration complete message to the MN 1402, and resume MCGtransmission. Note that it may be the case that both MCG and SCGtransmission is stopped during the handover to the new PCell.

FIG. 15 illustrates another possible scenario in which MCG failurerecovery is performed via a split SRB (e.g., SRB1). As shown, in 1508, aUE 1506, MN 1502, and SN 1504 may be configured to communicate in dualconnectivity mode. In 1510, the UE 1506 may determine that MCG linkfailure has occurred, but that the SCG link remains connected, and mayinitiate a MCG failure recovery procedure, including suspending MCGtransmission, continuing SCG data transmission, and transmitting MCGfailure information on the SRB1. In 1512, the SN 1504 may receive theMCG failure information via the SRB1, and may forward the SRB1 data(e.g., including the MCG failure information) to the MN 1502. In 1514,based on the MCG failure information, the MN 1502 may determine tohandover the PCell for the UE 1506 to the SN 1504. The MN 1502 and theSN 1504 may perform a handover procedure 1516, including the MN 1502providing a handover request to the SN 1504 via the X2 interface, andthe SN 1504 providing a handover request acknowledgement to the MN 1502via the X2 interface. The MN 1502 may provide RRC reconfigurationinformation for this RRC transfer to the SN 1504, which may in turnprovide the RRC reconfiguration information to the UE 1506, e.g., usingthe SRB1. In 1518, the UE 1506 may receive the RRC reconfigurationmessage, and may apply the indicated PCell configuration, transmit a RRCreconfiguration complete message to the SN 1504 (which may now becomethe master node with respect to the UE 1506), and resume MCGtransmission. Note that it may be the case that both MCG and SCGtransmission is stopped during the handover to the new PCell.

FIG. 16 illustrates another possible scenario in which MCG failurerecovery is performed via a SCG specific SRB (e.g., SRB3). As shown, in1608, a UE 1606, MN 1602, and SN 1604 may be configured to communicatein dual connectivity mode. In 1610, the UE 1606 may determine that MCGlink failure has occurred, but that the SCG link remains connected, andmay initiate a MCG failure recovery procedure, including suspending MCGtransmission, continuing SCG data transmission, and transmitting MCGfailure information on the SRB3. In 1612, the SN 1604 may receive theMCG failure information via the SRB3, and may forward the MCG failureinformation to the MN 1602 via X2 message. In 1614, based on the MCGfailure information, the MN 1602 may determine to handover the PCell forthe UE 1606 to the SN 1604. The MN 1602 and the SN 1604 may perform ahandover procedure 1616, including the MN 1602 providing a handoverrequest to the SN 1604 via the X2 interface, and the SN 1604 providing ahandover request acknowledgement to the MN 1602 via the X2 interface. In1618, the SN 1604 may assemble a SRB3 reconfiguration message forproviding a command to the UE 1606 indicating to handover to the SN1604, and may provide the RRC reconfiguration information to the UE1606, e.g., using the SRB3. In 1620, the UE 1606 may receive the RRCreconfiguration message, and may apply the indicated PCellconfiguration, transmit a RRC reconfiguration complete message to the SN1604 (which may now become the master node with respect to the UE 1606),e.g., using the SRB1, and resume MCG transmission. Note that it may bethe case that both MCG and SCG transmission is stopped during thehandover to the new PCell.

FIG. 17 illustrates aspects of possible use of a MCG recovery timer inconjunction with attempted MCG failure recovery via the SCG. As shown,in 1708, a UE 1706, MN 1702, and SN 1704 may be configured tocommunicate in dual connectivity mode. In 1710, the UE 1706 maydetermine that MCG link failure has occurred, but that the SCG linkremains connected, and may initiate a MCG failure recovery procedure,including suspending MCG transmission, continuing SCG data transmission,and transmitting MCG failure information on the SRB3. Additionally, theUE 1706 may start a MCG recovery timer when the MCG failure informationis transmitted. In 1712, the UE may determine that the MCG recoverytimer has expired, without successful MCG recovery, and may suspend alldata transmission, and initiate a UE connection re-establishmentprocedure.

FIG. 18 illustrates further aspects of possible use of a MCG recoverytimer in conjunction with attempted MCG failure recovery via the SCG. Asshown, in 1808, a UE 1806, MN 1802, and SN 1804 may be configured tocommunicate in dual connectivity mode. In 1810, the UE 1806 maydetermine that MCG link failure has occurred, but that the SCG linkremains connected, and may initiate a MCG failure recovery procedure,including suspending MCG transmission, continuing SCG data transmission,and transmitting MCG failure information on the SRB3. Additionally, theUE 1806 may start a MCG recovery timer when the MCG failure informationis transmitted. In 1812, the UE may determine that SCG link failure hasalso occurred, and may suspend all data transmission, and initiate a UEconnection re-establishment procedure (e.g., although the MCG recoverytimer may not yet have expired).

FIG. 19 illustrates aspects of a possible scenario in which both MCGfailure and SCG failure are detected. As shown, in 1908, a UE 1906, MN1902, and SN 1904 may be configured to communicate in dual connectivitymode. In 1910, the UE 1906 may determine that MCG link failure hasoccurred, and that SCG link failure has also occurred. Based on the MCGlink failure and the SCG link failure, the UE 1906 may suspend all datatransmissions, and may initiate a UE connection re-establishmentprocedure.

Thus, by using such techniques as described herein for performing MCGrecovery via the SCG, it may be possible to reduce or avoid datacommunication interruptions that might otherwise occur during MCG linkfailures, at least according to some embodiments.

In the following further exemplary embodiments are provided.

One set of embodiments may include an apparatus, comprising: aprocessing element configured to cause a wireless device to: establish afirst wireless link to a cellular network via a first cell group,wherein the first cell group is configured as a master cell group (MCG);establish a second wireless link to the cellular network via a secondcell group, wherein the second cell group is configured as a secondarycell group (SCG); determine that link failure for the first wirelesslink has occurred; and perform MCG link failure recovery using thesecond wireless link based at least in part on the link failure for thefirst wireless link.

According to some embodiments, to perform MCG link failure recovery viathe second wireless link, the processing element is further configuredto cause the wireless device to: suspend MCG transmission and reception;transmit MCG link failure information to the cellular network using thesecond wireless link; receive MCG reconfiguration information from thecellular network using the second wireless link; and resume MCGtransmission and reception using the MCG reconfiguration information.

According to some embodiments, the MCG link failure information includescause information for the link failure for the first wireless link.

According to some embodiments, the MCG link failure information includesmeasurement information for one or more of the first cell group or oneor more neighbor cells.

According to some embodiments, the MCG reconfiguration informationincludes one or more of: primary cell frequency information; primarycell band information; or primary cell resource configurationinformation.

According to some embodiments, the processing element is furtherconfigured to cause the wireless device to: initiate a MCG recoverytimer based at least in part on determining that link failure for thefirst wireless link has occurred; stop performing MCG link failurerecovery using the second wireless link if MCG link failure recovery hasnot yet succeeded when the MCG recovery timer expires.

According to some embodiments, the processing element is furtherconfigured to cause the wireless device to: determine that link failurefor the second wireless link has occurred; and stop performing MCG linkfailure recovery using the second wireless link based at least in parton determining that link failure for the second wireless link hasoccurred.

According to some embodiments, the processing element is furtherconfigured to cause the wireless device to: perform data transmissionwith the cellular network using the second wireless link while MCG linkfailure is occurring.

Another set of embodiments may include a wireless device, comprising anantenna; a radio coupled to the antenna; and a processing elementcoupled to the radio; wherein the wireless device is configured to:establish a first wireless link to a cellular network via a first cellgroup, wherein the first cell group is configured as a master cell group(MCG); establish a second wireless link to the cellular network via asecond cell group, wherein the second cell group is configured as asecondary cell group (SCG); determine that the wireless device isexperiencing MCG link failure; and transmit MCG link failure informationto the cellular network using the second wireless link.

According to some embodiments, the wireless device is further configuredto: determine cause information for the MCG link failure, wherein theMCG link failure information includes the cause information for the MCGlink failure.

According to some embodiments, the wireless device is further configuredto: perform one or more serving cell or neighboring cell measurementsbased at least in part on determining that the wireless device isexperiencing MCG link failure, wherein the MCG link failure informationincludes results of the one or more serving cell or neighboring cellmeasurements.

According to some embodiments, the wireless device is further configuredto: initiate a MCG recovery timer based at least in part on determiningthat the wireless device is experiencing MCG link failure; initiate aradio resource control connection re-establishment procedure if the MCGrecovery timer expires or if the wireless device also experiences SCGlink failure while experiencing MCG link failure.

According to some embodiments, wherein the wireless device is furtherconfigured to: receive MCG reconfiguration information using the secondwireless link, wherein the MCG reconfiguration information indicates oneor more of a modified primary cell frequency or a modified resourceconfiguration for the first wireless link.

According to some embodiments, the wireless device is further configuredto: receive MCG reconfiguration information using the second wirelesslink, wherein the MCG reconfiguration information indicates to handoverMCG for the wireless device to the second cell group.

Still another set of embodiments may include a first cellular basestation, comprising: an antenna; a radio coupled to the antenna; and aprocessing element coupled to the radio; wherein the first cellular basestation is configured to: establish a wireless link to a wirelessdevice, wherein the cellular base station provides a secondary cellgroup (SCG) for the wireless device; receive an indication from thewireless device using the wireless link that the wireless device isexperiencing master cell group (MCG) link failure; and provide theindication that the wireless device is experiencing MCG link failure toa second cellular base station, wherein the second cellular base stationprovides the MCG for the wireless device.

According to some embodiments, the first cellular base station isfurther configured to: receive MCG reconfiguration information for thewireless device from the second cellular base station; and provide anindication of the MCG reconfiguration information to the wireless deviceusing the wireless link.

According to some embodiments, the indication that the wireless deviceis experiencing MCG link failure is received using a signaling radiobearer that is split between the MCG and the SCG, wherein the indicationthat the wireless device is experiencing MCG link failure is provided tothe second cellular base station using the signaling radio bearer thatis split between the MCG and the SCG.

According to some embodiments, the indication that the wireless deviceis experiencing MCG link failure is received using a signaling radiobearer that is specific to the wireless link between the wireless deviceand the SCG, wherein the indication that the wireless device isexperiencing MCG link failure is provided to the second cellular basestation using a different signaling mechanism than the signaling radiobearer that is specific to the wireless link between the wireless deviceand the SCG.

According to some embodiments, the first cellular base station isfurther configured to: receive a request from the second cellular basestation to handover MCG for the wireless device to the first cellularbase station; provide a confirmation to the second cellular base stationto handover MCG for the wireless device to the first cellular basestation; and provide MCG reconfiguration information to the wirelessdevice using the wireless link, wherein the MCG reconfigurationinformation indicates to handover MCG for the wireless device to thefirst cellular base station.

According to some embodiments, the first cellular base station isfurther configured to: perform data transmission with the wirelessdevice using the wireless link while the wireless device is experiencingMCG link failure.

Yet another exemplary embodiment may include a method, comprising:performing, by a device, any or all parts of the preceding examples.

Still another exemplary embodiment may include a wireless device,comprising: an antenna; a radio coupled to the antenna; and a processingelement operably coupled to the radio, wherein the device is configuredto implement any or all parts of the preceding examples.

A further exemplary set of embodiments may include a non-transitorycomputer accessible memory medium comprising program instructions which,when executed at a device, cause the device to implement any or allparts of any of the preceding examples.

A still further exemplary set of embodiments may include a computerprogram comprising instructions for performing any or all parts of anyof the preceding examples.

A yet further exemplary set of embodiments may include an apparatuscomprising means for performing any or all of the elements of any of thepreceding examples.

It is well understood that the use of personally identifiableinformation should follow privacy policies and practices that aregenerally recognized as meeting or exceeding industry or governmentalrequirements for maintaining the privacy of users. In particular,personally identifiable information data should be managed and handledso as to minimize risks of unintentional or unauthorized access or use,and the nature of authorized use should be clearly indicated to users.

Embodiments of the present disclosure may be realized in any of variousforms. For example some embodiments may be realized as acomputer-implemented method, a computer-readable memory medium, or acomputer system. Other embodiments may be realized using one or morecustom-designed hardware devices such as ASICs. Still other embodimentsmay be realized using one or more programmable hardware elements such asFPGAs.

In some embodiments, a non-transitory computer-readable memory mediummay be configured so that it stores program instructions and/or data,where the program instructions, if executed by a computer system, causethe computer system to perform a method, e.g., any of a methodembodiments described herein, or, any combination of the methodembodiments described herein, or, any subset of any of the methodembodiments described herein, or, any combination of such subsets.

In some embodiments, a device (e.g., a UE 106) may be configured toinclude a processor (or a set of processors) and a memory medium, wherethe memory medium stores program instructions, where the processor isconfigured to read and execute the program instructions from the memorymedium, where the program instructions are executable to implement anyof the various method embodiments described herein (or, any combinationof the method embodiments described herein, or, any subset of any of themethod embodiments described herein, or, any combination of suchsubsets). The device may be realized in any of various forms.

Although the embodiments above have been described in considerabledetail, numerous variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.It is intended that the following claims be interpreted to embrace allsuch variations and modifications.

What is claimed is:
 1. An apparatus, comprising: a processor configuredto cause a wireless device to: establish a first wireless link to acellular network via a first cell group, wherein the first cell group isconfigured as a master cell group (MCG); establish a second wirelesslink to the cellular network via a second cell group, wherein the secondcell group is configured as a secondary cell group (SCG); determine thatlink failure for the first wireless link has occurred; suspend atransmission on the first wireless link; perform MCG link failurerecovery using the second wireless link based at least in part on thelink failure for the first wireless link, wherein MCG failure recoveryincludes transmitting MCG failure information on the second wirelesslink and starting a timer associated with transmitting the MCG failureinformation; and if, after initiation of MCG link failure recovery usingthe second wireless link, the timer expires, stop performing MCG linkfailure recovery using the second wireless link and initiate a RRCconnection re-establishment procedure.
 2. The apparatus of claim 1,wherein to perform MCG link failure recovery via the second wirelesslink, the processor is further configured to cause the wireless deviceto: transmit MCG link failure information to the cellular network usingthe second wireless link and using one of a split signaling radio bearerSRB1 or SRB3; receive MCG reconfiguration information from the cellularnetwork using the second wireless link; apply the MCG reconfigurationinformation to re-establish a MCG link; transmit an indication that theMCG reconfiguration is complete to the cellular network; and resume MCGtransmission and reception using the MCG link.
 3. The apparatus of claim2, wherein the MCG link failure information includes cause informationfor the link failure for the first wireless link.
 4. The apparatus ofclaim 2, wherein the MCG link failure information includes measurementinformation for one or more of the first cell group or one or moreneighbor cells.
 5. The apparatus of claim 2, wherein the MCGreconfiguration information includes one or more of: primary cellfrequency information; primary cell band information; or primary cellresource configuration information.
 6. The apparatus of claim 1, whereinsaid stopping performing MCG link failure recovery is performed inresponse to link failure for the second wireless link during the timer.7. The apparatus of claim 1, wherein the processor is further configuredto cause the wireless device to: perform data transmission with thecellular network using the second wireless link while MCG link failureis occurring.
 8. A wireless device, comprising: an antenna; a radiocoupled to the antenna; and a processing element coupled to the radio;wherein the wireless device is configured to: establish a first wirelesslink to a cellular network via a first cell group, wherein the firstcell group is configured as a master cell group (MCG); establish asecond wireless link to the cellular network via a second cell group,wherein the second cell group is configured as a secondary cell group(SCG); determine that link failure for the first wireless link hasoccurred; suspend a transmission on the first wireless link; perform MCGlink failure recovery using the second wireless link based at least inpart on the link failure for the first wireless link, wherein MCGfailure recovery includes transmitting MCG failure information on thesecond wireless link and starting a timer associated with transmittingthe MCG failure information; and if, after initiation of MCG linkfailure recovery using the second wireless link, the timer expires, stopperforming MCG link failure recovery using the second wireless link andinitiate a RRC connection re-establishment procedure.
 9. The wirelessdevice of claim 8, wherein the wireless device is further configured to:determine cause information for the MCG link failure; and wherein saidperforming MCG link failure recovery comprises transmitting MCG linkfailure information to the cellular network using the second wirelesslink, wherein the MCG link failure information includes the causeinformation for the MCG link failure.
 10. The wireless device of claim8, wherein the wireless device is further configured to: perform one ormore serving cell or neighboring cell measurements based at least inpart on determining that the wireless device is experiencing MCG linkfailure, wherein the MCG link failure information includes results ofthe one or more serving cell or neighboring cell measurements.
 11. Thewireless device of claim 8, wherein said stopping performing MCG linkfailure recovery is performed in response to link failure for the secondwireless link during the timer.
 12. The wireless device of claim 8,wherein the wireless device is further configured to: receive MCGreconfiguration information using the second wireless link, wherein theMCG reconfiguration information indicates one or more of a modifiedprimary cell frequency or a modified resource configuration for thefirst wireless link.
 13. The wireless device of claim 8, wherein thewireless device is further configured to: receive MCG reconfigurationinformation using the second wireless link, wherein the MCGreconfiguration information indicates to handover MCG for the wirelessdevice to the second cell group.
 14. The wireless device of claim 8,wherein to perform MCG link failure recovery via the second wirelesslink, the wireless device is configured to: transmit MCG link failureinformation to the cellular network using the second wireless link andusing one of a split signaling radio bearer SRB1 or SRB3; receive MCGreconfiguration information from the cellular network using the secondwireless link; apply the MCG reconfiguration information to re-establisha MCG link; transmit an indication that the MCG reconfiguration iscomplete to the cellular network; and resume MCG transmission andreception using the MCG link.
 15. A method for operating a wirelessdevice, comprising: by the wireless device: establishing a firstwireless link to a cellular network via a first cell group, wherein thefirst cell group is configured as a master cell group (MCG);establishing a second wireless link to the cellular network via a secondcell group, wherein the second cell group is configured as a secondarycell group (SCG); determining that link failure for the first wirelesslink has occurred; suspending a transmission on the first wireless link;performing MCG link failure recovery using the second wireless linkbased at least in part on the link failure for the first wireless link,wherein MCG failure recovery includes transmitting MCG failureinformation on the second wireless link and starting a timer associatedwith transmitting the MCG failure information; and if, after initiationof MCG link failure recovery using the second wireless link, the timerexpires, stopping performing MCG link failure recovery using the secondwireless link and initiate a RRC connection re-establishment procedure.16. The method of claim 15, further comprising: determining causeinformation for the MCG link failure; and wherein said performing MCGlink failure recovery comprises transmitting MCG link failureinformation to the cellular network using the second wireless link,wherein the MCG link failure information includes the cause informationfor the MCG link failure.
 17. The method of claim 15, furthercomprising: performing one or more serving cell or neighboring cellmeasurements based at least in part on determining that the wirelessdevice is experiencing MCG link failure, wherein the MCG link failureinformation includes results of the one or more serving cell orneighboring cell measurements.
 18. The method of claim 15, wherein saidstopping performing MCG link failure recovery is performed in responseto link failure for the second wireless link during the timer.
 19. Themethod of claim 15, further comprising: receiving MCG reconfigurationinformation using the second wireless link, wherein the MCGreconfiguration information indicates one or more of a modified primarycell frequency or a modified resource configuration for the firstwireless link.
 20. The method of claim 15, further comprising: receivingMCG reconfiguration information using the second wireless link, whereinthe MCG reconfiguration information indicates to handover MCG for thewireless device to the second cell group.